1. Field of the Invention
The present invention provides a process and an apparatus to transport a blow out preventer for a drilling or workover rig having a drawworks between a storage area and a use position over a wellbore. In particular, the present invention provides a running tool in order to move a blow out preventer between a storage area and a use position using the existing drawworks of a rig.
2. Prior Art
Uncontrolled blow outs of gas or oil from a subterranean well caused by rapid influx of formation fluid in the well bore at high pressure is to be avoided. Accordingly, blow out preventers (or BOPs) have been developed over the years for use in the oil and gas industry to prevent blow outs in drilling, workover and production operations. Blow out preventers are a series of valves and other devices which are installed at the wellhead of a well. From time to time, it is necessary to move the BOPs between a storage area and a use position over the wellhead. BOPs are extremely heavy structures, often many tons in weight and bulky.
In ocean drilling operations, many different decks are utilized in a drilling rig at different vertical heights above the wellhead. The BOP will be connected to the wellhead of a well above sea level. The various decks are at different heights above the level of the wellhead. To move the blow out preventer into position for use and then back to a storage position, the blow out preventer must be moved horizontally in a confined space between a pair of decks and then moved vertically through various decks. In ocean drilling operations, the rig is subject to environment conditions, such as lateral forces from wind and waves.
Prior devices to handle and move blow out preventers have included dedicated BOP handling systems with their own winch and movement mechanisms.
For example, Bolding (U.S. Pat. No. 4,367,796) discloses a cart for handling guidelines which rides on a truck. A separate BOP transfer cart to support a BOP. When the load of the BOP is transferred to a drilling string, the BOP support cart is moved away.
It would be advantageous to develop a BOP handling system which utilizes the existing block and tackle drawworks of a drilling or workover rig.
It would also be advantageous to develop a BOP handling system which could move a BOP both vertically and rotationally as well as provide lateral restraint.
It would also be advantageous to develop a BOP handling system that provides lateral restraint against forces from environmental conditions such as wind and wave energy.
It would also be advantageous to develop a BOP handling system that provides quick and simple attachment to a BOP.
It would also be advantageous to develop a BOP handling system that utilizes existing drilling rig skidding systems for BOP horizontal movement.